[PATCH] err.h: allow IS_ERR_VALUE to handle properly more types

From: Andrzej Hajda
Date: Thu Jan 07 2016 - 09:59:07 EST

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Current implementation of IS_ERR_VALUE works correctly only with
following types:
- unsigned long, unsigned long long,
- short, int, long.
Other types are handled incorrectly either on 32-bit either on 64-bit
either on both architectures.
The patch fixes it by comparing argument with MAX_ERRNO casted
to argument's type for unsigned types and comparing with zero for signed
types. As a result all integer types bigger than char are handled properly.

Signed-off-by: Andrzej Hajda <a.hajda@xxxxxxxxxxx>
---
Hi,

I have analyzed usage of IS_ERR_VALUE using coccinelle and in about 35 cases
it is used incorrectly, ie it can hide errors depending of 32/64 bit architecture.
Instead of fixing usage I propose to enhance the macro to cover more types.
And just for record: the macro is used 101 times with signed variables, I am not
sure if it should be preferred over simple comparison "ret < 0", but the new version
can do it as well.

In my previous attempt I have added type checking to the macro, I am not sure which
approach is better[1]. Anyway the previous patch did not catch developers attention.

[1]: http://permalink.gmane.org/gmane.linux.kernel/2111532

And below list of detected potential errors:
drivers/char/mem.c:698:45-46: WARNING: incorrect argument type in IS_ERR_VALUE(( unsigned long long ) offset)
drivers/media/platform/soc_camera/atmel-isi.c:1089:21-22: WARNING: incorrect argument type in IS_ERR_VALUE(irq)
drivers/net/ethernet/freescale/fs_enet/mac-scc.c:149:36-37: WARNING: incorrect argument type in IS_ERR_VALUE(fep -> ring_mem_addr)
drivers/net/ethernet/freescale/ucc_geth.c:2237:48-49: WARNING: incorrect argument type in IS_ERR_VALUE(ugeth -> tx_bd_ring_offset [ j ])
drivers/net/ethernet/freescale/ucc_geth.c:2314:48-49: WARNING: incorrect argument type in IS_ERR_VALUE(ugeth -> rx_bd_ring_offset [ j ])
drivers/net/ethernet/freescale/ucc_geth.c:2524:44-45: WARNING: incorrect argument type in IS_ERR_VALUE(ugeth -> tx_glbl_pram_offset)
drivers/net/ethernet/freescale/ucc_geth.c:2544:45-46: WARNING: incorrect argument type in IS_ERR_VALUE(ugeth -> thread_dat_tx_offset)
drivers/net/ethernet/freescale/ucc_geth.c:2571:46-47: WARNING: incorrect argument type in IS_ERR_VALUE(ugeth -> send_q_mem_reg_offset)
drivers/net/ethernet/freescale/ucc_geth.c:2612:42-43: WARNING: incorrect argument type in IS_ERR_VALUE(ugeth -> scheduler_offset)
drivers/net/ethernet/freescale/ucc_geth.c:2659:54-55: WARNING: incorrect argument type in IS_ERR_VALUE(ugeth -> tx_fw_statistics_pram_offset)
drivers/net/ethernet/freescale/ucc_geth.c:2696:44-45: WARNING: incorrect argument type in IS_ERR_VALUE(ugeth -> rx_glbl_pram_offset)
drivers/net/ethernet/freescale/ucc_geth.c:2715:45-46: WARNING: incorrect argument type in IS_ERR_VALUE(ugeth -> thread_dat_rx_offset)
drivers/net/ethernet/freescale/ucc_geth.c:2736:54-55: WARNING: incorrect argument type in IS_ERR_VALUE(ugeth -> rx_fw_statistics_pram_offset)
drivers/net/ethernet/freescale/ucc_geth.c:2756:53-54: WARNING: incorrect argument type in IS_ERR_VALUE(ugeth -> rx_irq_coalescing_tbl_offset)
drivers/net/ethernet/freescale/ucc_geth.c:2822:44-45: WARNING: incorrect argument type in IS_ERR_VALUE(ugeth -> rx_bd_qs_tbl_offset)
drivers/net/ethernet/freescale/ucc_geth.c:2908:47-48: WARNING: incorrect argument type in IS_ERR_VALUE(ugeth -> exf_glbl_param_offset)
drivers/net/ethernet/freescale/ucc_geth.c:292:36-37: WARNING: incorrect argument type in IS_ERR_VALUE(init_enet_offset)
drivers/net/ethernet/freescale/ucc_geth.c:3042:39-40: WARNING: incorrect argument type in IS_ERR_VALUE(init_enet_pram_offset)
drivers/soc/fsl/qe/ucc_fast.c:271:60-61: WARNING: incorrect argument type in IS_ERR_VALUE(uccf -> ucc_fast_tx_virtual_fifo_base_offset)
drivers/soc/fsl/qe/ucc_fast.c:284:60-61: WARNING: incorrect argument type in IS_ERR_VALUE(uccf -> ucc_fast_rx_virtual_fifo_base_offset)
drivers/soc/fsl/qe/ucc_slow.c:186:38-39: WARNING: incorrect argument type in IS_ERR_VALUE(uccs -> us_pram_offset)
drivers/soc/fsl/qe/ucc_slow.c:213:38-39: WARNING: incorrect argument type in IS_ERR_VALUE(uccs -> rx_base_offset)
drivers/soc/fsl/qe/ucc_slow.c:224:38-39: WARNING: incorrect argument type in IS_ERR_VALUE(uccs -> tx_base_offset)
drivers/tty/serial/clps711x.c:471:29-30: WARNING: incorrect argument type in IS_ERR_VALUE(s -> port . irq)
drivers/tty/serial/digicolor-usart.c:485:30-31: WARNING: incorrect argument type in IS_ERR_VALUE(dp -> port . irq)
drivers/usb/gadget/udc/fsl_qe_udc.c:2369:26-27: WARNING: incorrect argument type in IS_ERR_VALUE(tmp_addr)
drivers/video/fbdev/exynos/exynos_mipi_dsi.c:406:27-28: WARNING: incorrect argument type in IS_ERR_VALUE(dsim -> irq)
net/ipv4/netfilter/arp_tables.c:1427:39-40: WARNING: incorrect argument type in IS_ERR_VALUE(iter1 -> counters . pcnt)
net/ipv4/netfilter/arp_tables.c:530:34-35: WARNING: incorrect argument type in IS_ERR_VALUE(e -> counters . pcnt)
net/ipv4/netfilter/ip_tables.c:1614:34-35: WARNING: incorrect argument type in IS_ERR_VALUE(e -> counters . pcnt)
net/ipv4/netfilter/ip_tables.c:674:34-35: WARNING: incorrect argument type in IS_ERR_VALUE(e -> counters . pcnt)
net/ipv6/netfilter/ip6_tables.c:1624:34-35: WARNING: incorrect argument type in IS_ERR_VALUE(e -> counters . pcnt)
net/ipv6/netfilter/ip6_tables.c:687:34-35: WARNING: incorrect argument type in IS_ERR_VALUE(e -> counters . pcnt)
drivers/net/ethernet/freescale/fs_enet/mac-fcc.c:110:35-36: WARNING: unknown argument type in IS_ERR_VALUE(fpi -> dpram_offset)

Regards
Andrzej

include/linux/err.h | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/include/linux/err.h b/include/linux/err.h
index 56762ab..40eca39 100644
--- a/include/linux/err.h
+++ b/include/linux/err.h
@@ -18,7 +18,9 @@

#ifndef __ASSEMBLY__

-#define IS_ERR_VALUE(x) unlikely((x) >= (unsigned long)-MAX_ERRNO)
+#define IS_ERR_VALUE(x) ((typeof(x))(-1) < 0 \
+ ? unlikely((x) < 0) \
+ : unlikely((x) >= (typeof(x))-MAX_ERRNO))

static inline void * __must_check ERR_PTR(long error)
{
--
1.9.1

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Next message: tim . gardner: "[PATCH v4.4-rc8 0/4] x86/microcode/intel: Squelch frame size warnings"
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